Date: Wed, 23 Feb 2011 07:42:18

Author: Cliff Bettis

Subject: Re: Tin Foil Capacitor

Post:

The behavior of the dissectible capacitor depends on the nature of the
dielectric. For instance, if the usual demonstration is done with quartz
glass instead of soda glass, it will retain the charge on the plates.

Cliff

-----Original Message-----
From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On
Behalf Of Jerry DiMarco
Sent: Tuesday, February 22, 2011 6:53 PM
To: tap-l@lists.ncsu.edu
Subject: Re: [tap-l] Tin Foil Capacitor

I'm familiar with that demo but there are lots of other demos about
charge flowing into and out of capacitors, and capacitors powering
mechanical or electrical devices. Textbook treatment of the subject also
mention current flowing on to plates, and more current flowing on to plates
when a dielectric is inserted. Discussion of dielectrics is about the
dipoles that are formed due to the E-field between the plates. Only the
residual charge left over after a capacitor is discharged is attributed to
dielectric absorption. So where does all the charging current go?
If you claim the dielectric stores the charge, how does that explain
a capacitor's ability to act as a filter in a power supply, or as a source
of power in a remote location? How would you explain the action of an RC
circuit?


Jerry
D


At 2/22/2011 03:18 PM, you wrote:
>Jerry,
>
>If you take the capacitor apart and remove the dielectric, you can touch
>the plates together and will find that there is no (or only a tiny tiny
>fraction of the) charge on them. Put it back together and it will be
charged.
>
>Paul
>
>
>On Feb 22, 2011, at 2:31 PM, chuck britton wrote:
>
> > Vacuum polarization ! ? ! ? ! ?
> >
> >
> > At 12:30 PM -0700 2/22/11, Jerry DiMarco wrote:
> >> Taking one problem at a time, are you saying there is no charge
> deposited on the plates of a capacitor?
> >>
> >> Jerry D
> >>
> >>
> >> At 2/21/2011 03:28 PM, you wrote:
> >>> Jerry,
> >>>
> >>> But in the case of the rolled foil capacitor there are two foils and
> two insulators. The "charge" is actually held in the polarization of the
> dielectric and not on the surface of the conductors.
> >>> ......
> >>>
> >>> Paul
> >



From tap-l-owner@lists.ncsu.edu Wed Feb 23 09:43:30 2011

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